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Phosphoisoforms of insulin-like growth factor binding protein-1 in appropriate-for-gestational-age and
1Department of Obstetrics and Gynecology, Tokyo Women's Medical College, Japan. iwashita@bnn-net-or-jp
Insights
The proportion of non-phosphorylated insulin-like growth factor binding protein-1 (IGFBP-1) differs between preterm and term fetuses. IGFBP-1 phosphoisoform profiles vary with fetal growth, indicating their importance beyond total levels.
Area of Science:
- Endocrinology
- Perinatal Biology
- Biochemistry
Background:
- Insulin-like growth factor binding protein-1 (IGFBP-1) plays a crucial role in fetal growth.
- The phosphorylation status of IGFBP-1 can influence its biological activity.
- Understanding IGFBP-1 phosphoisoform dynamics is essential for assessing fetal development.
Purpose of the Study:
- To analyze IGFBP-1 phosphoisoforms in maternal and cord sera.
- To investigate the relationship between IGFBP-1 phosphoisoforms and fetal growth status (preterm vs. term, appropriate for gestational age vs. small for gestational age).
Main Methods:
- Separation of IGFBP-1 phosphoisoforms using non-SDS-polyacrylamide gel electrophoresis and immunoblot detection.
- Analysis of phosphoisoforms by anion exchange chromatography on High-Performance Liquid Chromatography (HPLC).
Main Results:
- The proportion of non-phosphorylated IGFBP-1 was higher in preterm fetuses compared to their mothers.
- IGFBP-1 phosphoisoform profiles differed between appropriate for gestational age (AGA) and small for gestational age (SGA) term fetuses.
- SGA fetuses showed increased phosphorylated IGFBP-1 and a lower proportion of non-phosphorylated IGFBP-1 compared to AGA fetuses.
Conclusions:
- Fetal growth status is associated with distinct IGFBP-1 phosphoisoform profiles.
- Both the total amount and the phosphoisoform composition of IGFBP-1 are significant factors in regulating fetal growth.
Abstract:
We analysed phosphoisoforms of insulin-like growth factor binding protein-1 (IGFBP-1) in maternal and cord sera from preterm and term fetus with different growth status. Phosphoisoforms were separated by non-SDS-polyacrylamide gel electrophoresis and detected by immunoblot. Phosphoisoforms were also analysed by anion exchange chromatography on HPLC. The proportion of non-phosphorylated IGFBP-1 to total IGFBP-1 was significantly higher in preterm fetus than in their mothers, however, the relative amounts of each IGFBP-1 isoforms were similar between preterm and term fetus. The levels of non-phosphorylated IGFBP-1 were similar between appropriate for gestational age (AGA) and small for gestational age (SGA) fetus at term, however, phosphorylated isoforms of IGFBP-1 were increased in SGA fetus compared to those of AGA fetus and the proportion of non-phosphorylated IGFBP-1 to total IGFBP-1 was lower in SGA fetus than those in AGA fetus. Thus, the profiles of non-phosphorylated and phosphorylated IGFBP-1 in the fetus varies corresponding to fetal growth suggesting that not only total amounts of IGFBP-1 but also the proportion of phosphoisoforms of IGFBP-1 is important for fetal growth.